While pyosys technically supports an external abc in installation, the attempt to always copy yosys-abc regardless would cause `make install` to crash.
`__init__.py` already handles yosys-abc not existing, so this just skips the install.
From https://github.com/YosysHQ/yosys/pull/5497#issuecomment-3561398279, for ENABLE_ABC=1 to be valid, either ABC must be linked (LINK_ABC=1), or it must be possible to spawn executables (DISABLE_SPAWN=0). This configuration (ENABLE_ABC=1 LINK_ABC=0 DISABLE_SPAWN=1) already fails compilation in `abc.cc` trying to call `run_command()` which doesn't exist if DISABLE_SPAWN=1. All we are doing here is catching the known bad configuration and providing an explanation for why it isn't working.
Add a sed command to the (top level) makefile for extract comment block for the specified cell. Works with both simlib.v and simcells.v (by abusing `%` pattern matching slightly to disambiguate which to search).
- add `uv` to dependencies: saves builder(s) from manually having to manage a venv for python build dependencies
- when building wheels, pip automatically creates the environment with those dependencies, so no need for uv
- when running simply `make ENABLE_PYOSYS=1`, this is not the case. people attempting to `pip3 install --upgrade pybind11 cxxheaderparser` to add it to their system packages will be met with a scare message about "breaking system packages"
- update installation instructions to drop boost and add uv instead
- update ci scripts to use `macos-15[-intel]` (`macos-13` sunset in early december)
